This application is for renewal of the Ruth L. Kirschstein National Research Service Award Postdoctoral Research Training Program (T32) in Pediatric Gastroenterology, Hepatology and Nutrition at the University of California, San Francisco (UCSF). The Program aims to train talented and dedicated young physicians to become independent and productive scientific investigators. These future scientists will research important health problems, focusing on the causes, pathogenesis, and treatment of digestive, liver and nutritional disorders in infants and children. Preference is given to trainees committed to a 4- year training program, including 3 years of research training in either Basic or Clinical/Translational Research mentored by established scientists. Basic research experience is supplemented with coursework, seminars, and inter-departmental retreats; trainees in clinical research all participate in the well-established Training in Clinical Research Program that includes a 2-year Master's Degree in Clinical Research. Each trainee pursues an obligatory research project(s) supervised by experienced preceptors. Entry requirements include a MD degree and 3 years of residency in clinical pediatrics. Applicants with a PhD degree and defined career goals related to developmental gastroenterology or nutrition are also eligible. Administration of the program is restructured to take advantage of the strengthened Division of Pediatric Gastroenterology/Nutrition under the primary direction of Dr. Melvin Heyman and associate direction from Dr. Philip Rosenthal. The quality of educational and research programs and activities will be closely monitored by trainee mentors, research preceptors, Internal Advisors, the Associate Program Director, the Program Director, and periodic evaluations by External Advisors. An increase from 3 to 4 training positions is requested in Years 36-40.